The invention relates to firearms, particularly shoulder arms and the like, which can be selectively operated in a continuous and a non-continuous manner.
Adjustable-mode firearms of this type are provided with a trigger mechanism including a hand-operated actuating lever, and an operating rod disposed above the trigger mechanism and longitudinally reciprocable between forward and rear positions. The operating rod has associated therewith a piston which reacts to the back gas pressure generated upon the firing of a cartridge forwardly through the barrel of the weapon to correspondingly move a cartridge chamber, which is coupled to the rear portion of the operating rod, from a closed-breech to an open-breech position to discharge the spent cartridge shell. Upon the next forward movement of the rod and the cartridge chamber, such chamber is again moved into a closed-breech position in which a new shell is guided into the chamber from a magazine disposed in the stock of the weapon. When the firearm is adjusted for continuous operation, such reciprocation of the operating rod and the associated components continues so long as the actuating lever in the trigger mechanism is held back and a firing pin associated with the rear of the cartridge chamber remains in an uncocked position. In the non-continuous mode, the operating rod comes to rest after each two-way reciprocation behind a projection disposed on a spring-loaded rocker arm which is withdrawable against the force of its spring each time the trigger is pulled.
Presently known firearm designs of this type are relatively expensive and heavy, and are difficult to service and maintain. The changeover in the trigger mechanism from continuous to non-continuous operation, and vice-versa, is relatively complicated as well.